1. Field of the Invention
The present invention is a new design having several advantages over the currently used endotracheal tubes.
2. Related Art
Patients requiring respiratory support in the form of mechanical ventilation often need an access to the airway in the form of endotracheal tube or tracheostomy tube. Endotracheal tube placement is also called intubation. In addition to providing an entry to the airway for mechanical ventilation it also serves as a port for clearing of respiratory secretions, delivering aerosolized medications such as albuterol, and other medical gases such as anesthetics, nitric oxide, helium. Presence of endotracheal tube also makes it easier to perform Fiberoptic bronchoscopy.
Once placed it is important that endotracheal tube stays inside the trachea until the duration that it is needed for. Inadvertent extubation is a frequent and serious complication of mechanical ventilation. The incidence of inadvertent extubation varies from 3% to 16% in adult population (1, 2, 3) and 2.7 to 5.5% in pediatric patients (4). Inadvertent extubation is associated with significant complications such as increased duration of mechanical ventilatory support, increased duration of hospital stay, and also increased incidence of nosocomial pneumonia (5,6).
There are several retrospective and some prospective studies showing that patient's age, severity of illness, the use of patient restraints, the method of sedation delivery, years of ICU nurse experience, and repositioning have no effect on the incidence of unplanned extubation (7).
Currently used endotracheal tubes are made up of PVC plastic, having a uniform curve and have a single distal port. Oral endotracheal tubes are secured at only one position on the tube with tape or other device to a patient's lip. The distal opening of the ET tube is fitted with an adapter which in turn is connected to ventilator tubings, in-line suction tubing, etc. An end-tidal carbon dioxide monitor and tidal volume monitor are sometimes interposed between the endotracheal tube adapter and ventilator tubing for closer monitoring. This contraption at the end of the endotracheal tube adds additional weight, keeping a constant pull on the ET tube in outward direction making it vulnerable for inadvertent extubation. This when added with some efforts from the patient or movement of the patient during transport or nursing care could result in inadvertent extubation.
Movement of patient's head and neck could result in movement of the ET tube in and out of patient's mouth when the tape comes loose, as for example from oral secretions. This movement of the tube can damage the inside of trachea by scraping the mucosa, making it prone to develop inflammatory edema initially and scarring and narrowing later, as shown in an animal model by Nakagishi et al (8).
Naso-tracheal intubation is an alternative option for accessing the airway. Nasal tubes are more easily anchored, have less extraneous movement, permit closure of mouth and are better tolerated by most patients. However, nasal tubes are associated with slightly higher morbidity than orotracheal tubes; these are longer, occasionally narrower and more prone for obstruction from secretions and kinking (9). They also offer a greater resistance to airflow.
The former endotracheal tubes are secured only at one area on the tube with a tape/device that is then secured at the lip or the nose. This process makes the endotracheal tubes vulnerable for inadvertent extubation and/or kinking especially with the weight of the attached tubings and paraphernalia that goes with it (such as in-line suction, CO2 sensors, etc.). The tape or securing device acts as fulcrum with a short arm as ventilator tubings with weights (in-line suction, end-tidal CO2 meter etc.) and a long arm as endotracheal tube, thus even a small movement at the short arm translates to a bigger movement of the long arm (endotracheal tube) resulting in inadvertent extubation.
The common features of current endotracheal tubes are: they are used to provide direct and unobstructed airway; they are made from special non-toxic, clear, thermo-sensitive siliconised PVC material to protect delicate mucosa; all tubes are fitted with 15-mm standard connector, which insures compatibility with circuit connectors; they provide full-length radio-opaque line to assess exact location of tube; they have 1-cm graduation markings to ascertain insertion depth; they are latex free; they are available in different sizes.
The main disadvantage of the current endotracheal tube is that it is liable for inadvertent extubation because:
a. It is difficult to secure
b. The weight of the tubings, and other paraphernalia makes ET tube unstable and precarious and prone to extubation and kinking.
c. Side to side movement of the head not only results in inadvertent extubation but also can be damaging to subglottic area and inner lining of the trachea.